This invention relates to shoes, and more particularly, to shoes which can be automatically adjusted in use to fit the users' foot under a wide range of usage and temperature conditions. For many years, the ski boot industry has tried to cope with the problem of comfortable fit for a boot. When the boots are cold, they are rather rigid and hard. When they heat up, they soften, which is the natural characteristics of thermoplastic material. Foam cushioning has been used as well as certain attempts which have been made to use an air-filled bladder within the shoes. Several years ago, a ski boot manufacturer used an air-filled inner boot which required an external pump to inflate the boot to an adequate pressure. This approach did not meet with commercial success, the problem being that a differential in temperature exists between indoor and outdoor conditions. Thus, a boot, or for another example, a sneaker, which is pumped up to fit indoors will be loose in colder outdoor temperatures. If the pressure is adjusted in the boot in a cold temperature and the person enters a warmer environment or, due to running, exercising, etc., heats up the air bladder within the footware, the footware becomes too tight as the pressure in the internal footware bladder builds up corresponding to the increased temperature.
In addition to this poor regulation of fit, it is necessary for the user to carry a pump in order to properly inflate the footware for the original fit.
What is needed is a high-tech boot, sneaker, or other footware which can be readily adjusted for proper fit with the user's foot, this adjustment being accomplished automatically and being automatically maintained regardless of changes in ambient conditions and degree of activity of the user.